[llvm] Eliminate pointless copies (PR #95097)

[Tim Gymnich via llvm-commits]

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@@ -27,11 +27,10 @@ class MemoryBuffer;
 /// that can be done by deriving from this class and overriding the destructor.
 class CachedFileStream {
 public:
-  CachedFileStream(std::unique_ptr<raw_pwrite_stream> OS,
-                   std::string OSPath = "")
+  CachedFileStream(std::unique_ptr<raw_pwrite_stream> OS, StringRef OSPath = "")
       : OS(std::move(OS)), ObjectPathName(OSPath) {}
   std::unique_ptr<raw_pwrite_stream> OS;
-  std::string ObjectPathName;
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tgymnich wrote:

String constructed for example on the stack may already be freed when using `CachedFileStream` at a later point since `StringRef` does not retain the string here.

https://github.com/llvm/llvm-project/pull/95097